Semiconductor device having metal interconnects with different thicknesses

ABSTRACT

An apparatus includes a first metal layer, a second metal layer and a dielectric material. The first metal layer has a first thickness and a second thickness less than the first thickness, and the first metal layer comprises a first interconnect having a first thickness. The dielectric material extends between the first and second metal layers and directly contacts the first and second metal layers. The dielectric material includes a via that extends through the dielectric material. A metal material of the via directly contacts the first interconnect and the second metal layer.

BACKGROUND

A typical integrated circuit includes electrically conductive tracescalled “interconnects” for purposes of electrically connectingcomponents of the integrated circuit together, as well as connectingthese elements to circuitry external to the integrated circuit. Theinterconnect cross-sectional area, the spacing between interconnects ofadjacent metal layers and the spacing between adjacent interconnects ofthe same metal layer may be factors contributing to an associatedresistance-capacitance (RC) product for the interconnect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2 and 3 are illustrations of dual thickness metal layers andinterconnects that are formed therein according to exampleimplementations.

FIGS. 4 and 6 depict semiconductor fabrication processes according toexample implementations.

FIGS. 5A, 5B, 5C, 5D, 5E and 5F depict stages of a process to fabricatemetal interconnects according to an example implementation.

FIGS. 7 and 8 are schematic diagrams of systems according to exampleimplementations.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like structures maybe provided with like suffix reference designations. In order to showthe structures of various implementations more clearly, the drawingsincluded herein are diagrammatic representations ofsemiconductor/circuit structures. Thus, the actual appearance of thefabricated integrated circuit structures, for example in aphotomicrograph, may appear different while still incorporating theclaimed structures of the illustrated implementations. Moreover, thedrawings may only show the structures useful to understand theillustrated implementations. Additional structures known in the art maynot have been included to maintain the clarity of the drawings. Forexample, not every layer of a semiconductor device is necessarily shown.“An implementation”, “various implementations” and the like indicateimplementation(s) so described may include particular features,structures, or characteristics, but not every implementation necessarilyincludes the particular features, structures, or characteristics. Someimplementations may have some, all, or none of the features describedfor other implementations. “First”, “second”, “third” and the likedescribe a common object and indicate different instances of likeobjects are being referred to. Such adjectives do not imply objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner. “Connected” may indicate elements arein direct physical or electrical contact with each other and “coupled”may indicate elements co-operate or interact with each other, but theymay or may not be in direct physical or electrical contact.

In general, the lower the resistance-capacitance (RC) product for ametal interconnect, the faster that a signal may propagate over theinterconnect. One way to achieve a lower RC product for a metalinterconnect is increase the interconnect's cross-sectional area,thereby decreasing the interconnect's resistance. For a fabricationprocess in which a metal interconnect is formed in a layer that has asingle thickness (herein called a “single thickness metal layer”), thecross-sectional area of the metal interconnect may be increased byincreasing the cross-sectional width of the interconnect.

Another way to achieve a lower RC product for a metal interconnect in asingle thickness metal layer fabrication process is to increase theeffective thickness of the interconnect by forming the interconnect fromtwo metal layers and connecting these layers using vias.

The RC product may not be the only consideration when laying out theinterconnects of an integrated circuit. For example, a given set ofmetal interconnects may not be used for high speed signal routing, andthe density of these metal interconnects may be more important thantheir associated RC products. To achieve a higher density for the metalinterconnects, a relatively narrow interconnect width may be used.

In accordance with example implementations that are described herein, anintegrated circuit has a metal layer, which has multiple thicknesses. Inexample implementations that are described herein, the metal layer hastwo thicknesses (hence, herein called a “dual thickness metal layer”),and metal interconnects are fabricated from these two thicknesses (i.e.,the interconnect either has a “single” thickness or a “double”thickness) to impart different associated RC products and interconnectdensities. More specifically, in accordance with exampleimplementations, the integrated circuit has metal interconnects forsignal routing, which have double thicknesses to impact lower associatedRC products, and the integrated circuit has metal interconnects, whichhave single thicknesses and are used to achieve a relatively higherassociated interconnect density.

For a given metal interconnect, the RC product of the interconnect is afunction of the R resistance of the interconnect, which is determined bythe interconnect's cross-sectional area and several factors that affectthe C capacitance: the surface areas between adjacent interconnects (ofthe same metal layer or adjacent metal layers), the intralayerinterconnect spacing and the interlayer interconnect spacing. Ingeneral, the smaller the spacing between adjacent metal interconnects ofthe same metal layer, the larger the C capacitance, and vice versa.

FIG. 1 depicts an example dual thickness metal layer 100, in accordancewith an example implementation. More specifically, for this example,FIG. 1 depicts a pair of metal interconnects 110 that are used forsignal routing (where the associated RC products are more important) anda pair of metal interconnects 120 used for higher density applications(where associated RC products are less important than an intralayerdistance Y between adjacent interconnects 120). As shown in FIG. 1 , themetal interconnect 110 has a thickness 113 that is twice the thickness121 of the metal interconnect 120.

In the notation that is used in FIG. 1 , the thickness 113 refers to thedimension of the metal interconnect 110 along a depth dimension z (seeaxes 101) of the integrated circuit. In this context, the depthdimension z extends through the layers of the integrated circuit; andaxes x and y that are orthogonal to the z axis laterally extend along agiven layer. The metal interconnect 110, 120 longitudinally extendsalong the y axis for this example, and the cross-sectional area of theinterconnect 110, 120 has the thickness 113 dimension along the z axisand a width 115 dimension along the x axis.

In the notation used in FIG. 1 and subsequent figures, the “X_(WIDE)”label is used to denote the equivalent width of a hypothetical metalinterconnect that has the same resistance and is formed in a singlethickness metal layer, and the “T” label is used to denote theequivalent thickness of this hypothetical interconnect. Thus, in FIG. 1, the metal interconnect 110 of the dual thickness metal layer 100 has athickness 113 and a width 115, which corresponds to a width and athickness, respectively, of a metal interconnect fabricated from asingle thickness metal layer and having the same resistance (i.e., theinterconnect 110 shown in FIG. 1 is rotated 90° from a correspondinginterconnect formed from a single thickness metal layer, for example).

As also depicted in FIG. 1 , the metal interconnects 120 are spacedapart by the Y distance. Moreover, for this example, the interconnects110 are spaced apart according to a pitch 117 (i.e., thecenter-to-center distance between adjacent interconnects 110), whichdefines the footprint for the interconnect 110. The metal interconnectsare separated by a distance X_(WIDE)+Y−T.

As compared to conventional interconnects that are formed in a singlethickness metal layer, the metal interconnects 110 have a reduced Ccapacitance for the same resistance. In this manner, as noted above,such a metal interconnect may have a thickness T and a width X_(WIDE).As depicted in FIG. 1 , however, due to dual metal thicknesses of themetal layer 100, the interconnect 110 is rotated ninety degrees (ascompared to the conventional metal interconnect) so that the separation119 of the interconnects 110 (i.e., X_(WIDE)+Y−T) is increased; and assuch, the interconnects 110 are spaced apart farther than the Y spacingof the interconnects 120. Thus, in summary, the interconnects 110 mayhave the same footprint as conventional interconnects having the samecross-sectional area, but the interconnect 110 has a lower C capacitance(and thus a lower associated RC product) due to the increased intralayerinterconnect spacing that is available due to the dual thickness metallayer 100.

As a more specific example, the T width may be 50 nanometers (nm), theX_(WIDE) thickness may be 100 nm, and the Y spacing may be 20 nm. Withthe conventional interconnect, the left/right capacitance (i.e.,capacitances between adjacent metal interconnects), is proportional toT/Y=C*2.5. With the dual thickness metal layer 100 of FIG. 1 , however,the left/right capacitance is proportional toX_(WIDE)/(X_(WIDE)+Y−T)=C*1.4. Therefore, this a 44% reduction incapacitance, only considering the left/right capacitance.

Referring to FIG. 2 , as another variation, a dual thickness metal layer200 may be used to fabricate metal interconnects 210 for signal routingand interconnects 120 for higher density interconnect applications. Forthis example implementation, the metal interconnects 210 have the samefootprint (i.e., the same pitch 117) as the metal interconnects 110(FIG. 1 ), but the metal interconnects 210 have lower R resistances.More specifically, as depicted in FIG. 2 , as compared to theinterconnect 110, a width 215 (also called “X_(WIDE2)” herein) isincreased, thereby increasing the cross-sectional area of theinterconnect 210 to lower its R resistance. Therefore, the RC productassociated with the metal interconnect 210 is decreased, whilemaintaining the same footprint.

Considering the example parameters that are set forth above, theleft/right capacitance is kept unchanged at C₁*2.5 with a spacing ofY₂=40 nm. This allows the metal line width X_(WIDE2) to be 80 nm. As aresult, the metal cross-sectional area is increased from T*X_(WIDE) toX_(WIDE)*X_(WIDE2). The R resistance is lowered by 37.5% for thisexample implementation.

Referring to FIG. 3 , in accordance with another example implementation,a dual thickness metal layer 300 may include interconnects 310 that havethe same associated RC products as interconnects formed from a singlethickness metal layer, but the interconnects 310 have a relativelysmaller footprint, i.e., the interconnects 310 have an associated pitch317 that is decreased. In this manner, the metal interconnect 310 hasthe same cross-sectional dimensions as the metal interconnect 110 ofFIG. 1 , with the associated pitch 317 being less than the pitch 117(FIG. 1 ).

Thus, the capacitance benefit may be forfeited in exchange of area, inaccordance with example implementations, to achieve C₁*2.5,X_(WIDE)/(Pitch−T)=2.5. For a new pitch 311 of 90 nm, compared toX_(WIDE)+Y=120 nm, this is a 0.75X area scaling.

Particular advantages of the metal interconnects that are describedherein are that costs may be reduced and fabrication time may be reducedfor fabricating high density and signal routing metal interconnects, asmask costs and processing complexity are reduced. Other advantages arecontemplated, in accordance with further example implementations.

Referring to FIG. 4 , in accordance with example implementations, atechnique 400 may be used for purposes of forming interconnects on asubstrate 500, which contains a dielectric layer 510 that overlays ametal layer 512, as illustrated in FIG. 5A. As examples, the substrate500 may be silicon, germanium, gallium arsenide, gallium nitride, or anysemiconductor. As examples, the metal layer 512 may be copper, aluminum,tungsten, nickel, platinum, gold, silver or palladium. As examples, thedielectric layer 510 may be silicon oxide, silicon nitride, siliconoxynitride, fluorine doped silicon dioxide, carbon doped silicon dioxideor an organic polymer.

Pursuant to block 404 of the technique 400, a first metal line 526 (seeFIG. 5C) and a second metal line 524 (FIG. 5C) that is parallel to thefirst metal line 526 are formed on the substrate 500. As examples, thefirst metal line 526 and the second metal line 524 may be formed fromone of the metals that are mentioned above for the metal layer 512. Thefirst metal line 526 has a double thickness and forms a first metalinterconnect 527 (see FIG. 5F). Pursuant to block 408 of the technique400, a mask (a photoresist mask 530 of FIG. 5D, for example) is formedover the first metal line 526. Pursuant to block 412 of a technique 400,a portion 540 (see FIG. 5E) of the second metal line 524 is removed fromthe second metal line 524 to form a second metal interconnect 550 (seeFIG. 5F). As depicted in FIG. 5F, a thickness of the first metalinterconnect 527 is greater than a thickness of the second metalinterconnect 550. Pursuant to block 416 of the technique 400, adielectric layer is formed on the first 527 and second 550 metalinterconnects, as illustrated in FIG. 5F. The dielectric layer may beany of the materials mentioned above for the dielectric layer 510.

More specifically, referring to FIG. 6 in conjunction with FIGS. 5A to5F, a technique 600 includes forming (block 604) a resist pattern (notshown) on the dielectric layer 510 (see FIG. 5A) to define regions to beetched corresponding to thick metal interconnects, thin metalinterconnects, and vias. Pursuant to block 608 of the technique 600, thepatterns on which the resist pattern were formed are used to etchregions of the dielectric layer 510 corresponding to the thick metalinterconnects, the thin metal interconnects and the vias. As an example,FIG. 5B depicts etching of the dielectric layer 510 to form troughs, orrecesses 514, 516 and 518, which correspond to recesses used to form athin metal interconnect, a thick metal interconnect, and a via,respectively.

Referring to FIG. 6 in conjunction with FIG. 5C, the technique 600includes depositing (block 612) metal in the etched regions of thedielectric layer 510 to form the corresponding metal lines 524 and 526,as well as deposit metal in the recess 518 to form a via 529. Asexamples, the metal deposited to form the via 529 may be copper,aluminum, tungsten, nickel, platinum, gold, silver or palladium. Asdiscussed above, the first metal line 526 corresponds to the thick metalinterconnect 527. Pursuant to block 616 of the technique 600, thephotoresist pattern 530 has been formed to mask regions corresponding tothe thick metal interconnects, as depicted in FIG. 5D.

Next, referring to FIG. 6 in conjunction with FIG. 5E, the unmaskedregions are etched (block 620) to remove portions (such as illustratedportions 540 and 544 of FIG. 5E) of the substrate 500. These portionsinclude deposited metal for purposes of forming the thin metalinterconnect. In this manner, as shown in FIG. 5E, removal of the metalline 524 (see also FIG. 5D) produces the relatively thin metalinterconnect 550. Lastly, pursuant to the technique 600, a dielectriclayer is deposited to prepare the substrate 510 for the next metallayer. In this manner, as depicted in FIG. 5F, a dielectric layer isdeposited in the portions (such as portions as 540 and 544 of FIG. 5E,for example) that were etched.

Referring now to FIG. 7 , in accordance with example implementations, asystem 900 may include integrated circuits, which contain metalinterconnects having different thicknesses, as described herein. Thesystem 900, may be, as examples, a smartphone, a wireless communicator,or any other IoT device. A baseband processor 905 is configured to anapplication processor 910, which may be a main CPU of the system toexecute an OS and other system software, in addition to userapplications such as many well-known social media and multimedia apps.Application processor 910 may further be configured to perform a varietyof other computing operations for the device.

In turn, application processor 910 can couple to a userinterface/display 920 (e.g., touch screen display). In addition,application processor 910 may couple to a memory system including anon-volatile memory, namely a flash memory 930 and a system memory,namely a DRAM 935. In some implementations, flash memory 930 may includea secure portion 932 in which secrets and other sensitive informationmay be stored. As further seen, application processor 910 also couplesto a capture device 945 such as one or more image capture devices thatcan record video and/or still images.

A universal integrated circuit card (UICC) 940 includes a subscriberidentity module, which in some implementations includes a secure storage942 to store secure user information. System 900 may further include asecurity processor 950 (e.g., Trusted Platform Module (TPM)) that maycouple to application processor 910. A plurality of sensors 925,including one or more multi-axis accelerometers may couple toapplication processor 910 to enable input of a variety of sensedinformation such as motion and other environmental information. Inaddition, one or more authentication devices 995 may be used to receive,for example, user biometric input for use in authentication operations.

As further illustrated, a near field communication (NFC) contactlessinterface 960 is provided that communicates in a NFC near field via anNFC antenna 965. While separate antennae are shown, understand that insome implementations one antenna or a different set of antennae may beprovided to enable various wireless functionalities.

A power management integrated circuit (PMIC) 915 couples to applicationprocessor 910 to perform platform level power management. To this end,PMIC 915 may issue power management requests to application processor910 to enter certain low power states as desired. Furthermore, based onplatform constraints, PMIC 915 may also control the power level of othercomponents of system 900.

To enable communications to be transmitted and received such as in oneor more IoT networks, various circuitries may be coupled betweenbaseband processor 905 and an antenna 990. Specifically, a radiofrequency (RF) transceiver 970 and a wireless local area network (WLAN)transceiver 975 may be present. In general, RF transceiver 970 may beused to receive and transmit wireless data and calls according to agiven wireless communication protocol such as 3G or 4G wirelesscommunication protocol such as in accordance with a code divisionmultiple access (CDMA), global system for mobile communication (GSM),long term evolution (LTE) or other protocol. In addition a GPS sensor980 may be present, with location information being provided to securityprocessor 950 for use as described herein when context information is tobe used in a pairing process. Other wireless communications such asreceipt or transmission of radio signals (e.g., AM/FM) and other signalsmay also be provided. In addition, via WLAN transceiver 975, localwireless communications, such as according to a Bluetooth™ or IEEE802.11 standard can also be realized.

Referring to FIG. 8 , in accordance with further exampleimplementations, a multiprocessor system 1000, such as a point-to-pointinterconnect system (a server system, for example), may includeintegrated circuits having dual thickness metal interconnects, asdescribed herein. The system 1000 may include a first processor 1070 anda second processor 1080 coupled via a point-to-point interconnect 1050.Each of processors 1070 and 1080 may be multicore processors such asSoCs, including first and second processor cores (i.e., processor cores1074 a and 1074 b and processor cores 1084 a and 1084 b), althoughpotentially many more cores may be present in the processors. Inaddition, processors 1070 and 1080 each may include a secure engine 1075and 1085 to perform security operations such as attestations, IoTnetwork onboarding or so forth.

In accordance with example implementations, one or multiple integratedcircuits or semiconductor devices may include interconnects that aredisclosed herein, such as, for example, interconnects in integratedcircuits containing the processor 910, the processor 1070, the memory935, the memory 932, the memory 1032, the memory 1034 or the memory1028, as just a few examples.

First processor 1070 further includes a memory controller hub (MCH) 1072and point-to-point (P-P) interfaces 1076 and 1078. Similarly, secondprocessor 1080 includes a MCH 1082 and P-P interfaces 1086 and 1088.MCH's 1072 and 1082 couple the processors to respective memories, namelya memory 1032 and a memory 1034, which may be portions of main memory(e.g., a DRAM) locally attached to the respective processors. Firstprocessor 1070 and second processor 1080 may be coupled to a chipset1090 via P-P interconnects 1052 and 1054, respectively. Chipset 1090includes P-P interfaces 1094 and 1098.

Furthermore, chipset 1090 includes an interface 1092 to couple chipset1090 with a high performance graphics engine 1038, by a P-P interconnect1039. In turn, chipset 1090 may be coupled to a first bus 1016 via aninterface 1096. Various input/output (I/O) devices 1014 may be coupledto first bus 1016, along with a bus bridge 1018 which couples first bus1016 to a second bus 1020. Various devices may be coupled to second bus1020 including, for example, a keyboard/mouse 1022, communicationdevices 1026 and a data storage unit 1028 such as a non-volatile storageor other mass storage device. As seen, data storage unit 1028 mayinclude code 1030, in one implementation. As further seen, data storageunit 1028 also includes a trusted storage 1029 to store sensitiveinformation to be protected. Further, an audio I/O 1024 may be coupledto second bus 1020.

Other implementations are contemplated and are within the scope of theappended claims. For example, in some implementations, a communicationdevice may be arranged to perform the various and techniques describedherein. In accordance with further example implementations, a deviceother than a communication device may be arranged to perform the variousmethods and techniques described herein.

Implementations may be used in many different types of systems. Forexample, in one implementation a communication device can be arranged toperform the various methods and techniques described herein. Of course,the scope of the present invention is not limited to a communicationdevice, and instead other implementations can be directed to other typesof apparatus for processing instructions, or one or more machinereadable media including instructions that in response to being executedon a computing device, cause the device to carry out one or more of themethods and techniques described herein.

In accordance with example implementations, the techniques of FIGS. 4and 6 may be implemented by executing machine executable instructions,or “program code,” which is stored on non-transitory media. In thismanner, the program code, when executed by one or multiple centralprocessing unit(s), (one or multiple processing cores, and so forth) maycause the processor to fabricate at least one integrated circuit toperform one or multiple operations. Implementations (e.g., code forimplementing the processes of FIGS. 4 and 6 ) may be implemented in codeand may be stored on a non-transitory storage medium having storedthereon instructions which can be used to program a system to performthe instructions. Implementations also may be implemented in data andmay be stored on a non-transitory storage medium, which if used by atleast one machine, causes the at least one machine to fabricate at leastone integrated circuit to perform one or more operations. As examples,the storage media may include semiconductor storage devices, magneticstorage devices, optical storage devices, and so forth. As more specificexamples, the storage media may include floppy disks, optical disks,solid state drives (SSDs), compact disk read-only memories (CD-ROMs),compact disk rewritable (CD-RWs), and magneto-optical disks,semiconductor devices such as read-only memories (ROMs), random accessmemories (RAMs) such as dynamic random access memories (DRAMs), staticrandom access memories (SRAMs), erasable programmable read-only memories(EPROMs), flash memories, electrically erasable programmable read-onlymemories (EEPROMs), magnetic or optical cards, or any other type ofmedia suitable for storing electronic instructions.

The following examples pertain to further implementations.

Example 1 includes an apparatus that includes a first metal layer havinga first thickness and a second thickness less than the first thickness,where the first metal layer includes a first interconnect having thefirst thickness; a second metal layer; a dielectric material extendingbetween the first and second metal layers and directly contacting thefirst and second metal layers, the dielectric material that includes avia extending through the dielectric material; and a metal material ofthe via to directly contact the first interconnect and the second metallayer.

In Example 2, the subject matter of Example 1 can optionally include thefirst metal layer including a second interconnect that is parallel tothe first interconnect; and the second interconnect having the firstthickness.

In Example 3, the subject matter of Examples 1-2 can optionally includethe first metal layer including a third interconnect and a fourthinterconnect parallel to the fourth interconnect; the secondinterconnect being spaced apart from the first interconnect by a firstdistance; and the fourth interconnect being spaced apart from the thirdinterconnect by a second distance less than the first distance.

In Example 4, the subject matter of Examples 1-3 can optionally includethe first distance being substantially the sum of the first thicknessand the second distance being less than a cross-sectional width of thefirst interconnect.

In Example 5, the subject matter of Examples 1-4 can optionally includethe third interconnect having a cross-sectional width; the firstinterconnect having a cross-sectional width that is greater than thecross-sectional width of the third interconnect; and the first distancebeing substantially the sum of the first thickness and the secondthickness less a cross-sectional width of the first interconnect.

In Example 6, the subject matter of Examples 1-5 can optionally includethe third interconnect having a cross-sectional width; the firstinterconnect having a cross-sectional width that is substantially thesame as the cross-sectional width of the third interconnect; and thefirst distance being substantially the sum of the first thickness andthe second thickness less a cross-sectional width of the firstinterconnect.

In Example 7, the subject matter of Examples 1-6 can optionally includethe first interconnect having a substantially uniform cross-sectionalwidth.

In Example 8, the subject matter of Examples 1-7 can optionally includethe cross-sectional width of the first interconnect being less than thefirst thickness.

In Example 9, the subject matter of Examples 1-8 can optionally includethe first metal layer further including another interconnect parallel tothe first interconnect; and the another interconnect having the secondthickness and a cross-sectional width that is substantially the same asa cross-sectional width of the first interconnect.

In Example 10, the subject matter of Examples 1-9 can optionally includethe first metal layer further including another interconnect parallel tothe first interconnect; and the another interconnect having the secondthickness and a cross-sectional width that is smaller than across-sectional width of the first interconnect.

In Example 11, the subject matter of Examples 1-10 can optionallyinclude a system-on-chip (SoC) that includes the first metal layer, thesecond metal layer, the dielectric material and the metal material.

Example 12 includes a system including a memory; and a processor coupledto the memory. At least one of the processor and the memory includes anapparatus according to any one of Examples 1 to 11.

Example 13 includes a method that includes forming a first metal lineand a second metal line parallel to the first metal line on a substrate,where the first metal line includes a first metal interconnect; forminga mask over the first metal interconnect; removing a portion of thesecond metal line to form a second interconnect from a remaining portionof the second metal line, where a thickness of the first interconnect isgreater than a thickness of the second interconnect; and forming andielectric layer on the first and second interconnects.

In Example 14, the subject matter of Example 13 can optionally includeforming the first metal line and the second metal line on the substrateincluding masking the dielectric layer for the first and second metallines; removing a first portion of the dielectric layer to form a firsttrench corresponding to the first metal line; and removing a secondportion of the dielectric layer to form a second trench corresponding tothe second metal line.

In Example 15, the subject matter of Examples 13-14 can optionallyinclude forming the first metal line and the second metal line furtherincluding depositing a metal in the first and second trenches.

In Example 16, the subject matter of Examples 13-15 can optionallyinclude making the dielectric layer for a via extending to the firstmetal line; and removing a third portion of the dielectric layercorresponding to the via.

In Example 17, the subject matter of Examples 13-16 can optionallyinclude depositing a metal in the first trench and in the via to formthe first metal line and a direct connection between the first metalline and a metal layer on the substrate other than a metal layercontaining the first metal line.

In Example 18, the subject matter of Examples 13-17 can optionallyinclude forming the first metal line and the second metal line includingdepositing metal associated with a single metal layer.

Example 19 includes an apparatus that includes a first metal layerhaving a first thickness and a second thickness less than the firstthickness, where the first metal layer includes a first plurality ofparallel interconnects and each interconnect of the first plurality ofinterconnects has a first thickness; and a second plurality of parallelinterconnects, where each interconnect of the second plurality ofinterconnects has a second thickness less than the first thickness; asecond metal layer; a dielectric material extending between the firstand second metal layers and directly contacting the first and secondmetal layers, where the dielectric material that includes a viaextending through the dielectric material; and a metal material of thevia to directly contact the second metal layer and at least one of theinterconnects of the first plurality of parallel interconnects.

In Example 20, the subject matter of Example 19 may optionally includethe first plurality of interconnects having an associated first spacingbetween adjacent interconnects of the first plurality of parallelinterconnects; the second plurality of interconnects having anassociated second spacing between adjacent interconnects of the secondplurality of parallel interconnects; and the second spacing being lessthan the first spacing.

In Example 21, the subject matter of Examples 19-20 can optionallyinclude the first plurality of interconnects being parallel to a firstaxis and the thickness of each interconnect of the first plurality ofinterconnects corresponding to a dimension measured along a second axisorthogonal to the first axis.

The foregoing description of the implementations of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseforms disclosed. This description and the claims following includeterms, such as left, right, top, bottom, over, under, upper, lower,first, second, etc. that are used for descriptive purposes only and arenot to be construed as limiting. For example, terms designating relativevertical position refer to a situation where a device side (or activesurface) of a substrate or integrated circuit is the “top” surface ofthat substrate; the substrate may actually be in any orientation so thata “top” side of a substrate may be lower than the “bottom” side in astandard terrestrial frame of reference and still fall within themeaning of the term “top.” The term “on” as used herein (including inthe claims) does not indicate that a first layer “on” a second layer isdirectly on and in immediate contact with the second layer unless suchis specifically stated; there may be a third layer or other structurebetween the first layer and the second layer on the first layer. Theimplementations of a device or article described herein can bemanufactured, used, or shipped in a number of positions andorientations. Persons skilled in the relevant art can appreciate thatmany modifications and variations are possible in light of the aboveteaching. Persons skilled in the art will recognize various equivalentcombinations and substitutions for various components shown in theFigures. It is therefore intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

What is claimed is:
 1. A method comprising: forming a first metal lineand a second metal line parallel to the first metal line on a substrate,wherein the first metal line comprises a first metal interconnect;forming a mask over the first metal interconnect; removing a portion ofthe second metal line to form a second interconnect from a remainingportion of the second metal line, wherein a thickness of the firstinterconnect along a depth dimension is greater than a thickness of thesecond interconnect along the depth dimension; and forming a dielectriclayer on the first and second interconnects.
 2. The method of claim 1,wherein forming the first metal line and the second metal linecomprises: masking the dielectric layer for the first and second metallines; removing a first portion of the dielectric layer to form a firsttrench corresponding to the first metal line; and removing a secondportion of the dielectric layer to form a second trench corresponding tothe second metal line.
 3. The method of claim 2, wherein forming thefirst metal line and the second metal line further comprises depositinga metal in the first and second trenches.
 4. The method of claim 1,further comprising: masking the dielectric layer for a via extending tothe first metal line; and removing a third portion of the dielectriclayer corresponding to the via.
 5. The method of claim 4, furthercomprising: depositing a metal in the first trench and in the via toform the first metal line and a direct connection between the firstmetal line and a metal layer on the substrate other than a metal layercontaining the first metal line.
 6. The method of claim 1, whereinforming the first metal line and the second metal line comprisesdepositing metal associated with a single metal layer.